大Peclect数多粒径分布球形多孔介质内流动、传质和反应特性的研究

The characteristics of two components flow, mass transfer and reaction at large Peclet numbers are studied systematically for optimized design of the inner structure and operation and control in porous media made by multi-particulate distribution, combining numerical simulation with experimental and published data. At first, lattice Botlzmann Method (LBM) and Random-walk particle tracer Method (RWM) are developed because LBM has advantages in the problems with complicated boundaries and RWM is good for the convection-diffusion processes with large Peclet numbers, and the mathematical equations on flow, mass transfer and chemical reaction in porous media are built up. The geometry models of porous media with different particle sizes are created by that the sedimentation process of particles is simulated by LBM. The mathematical models are verified by experimental and published data, and then we simulate the flow, mass transfer and reaction for two components in porous media made randomly. Based on the effects of large Peclet number and particle size distribution on flow, mass transfer and chemical reaction processes, we can design the pore structure of porous media and optimize and control the operation.

本项目以解决固体酸烷基化固定床反应器的多孔介质内部结构设计和操作优化控制为研究背景，以数值模拟为主、结合实验和文献数据验证，研究多粒径分布的球形颗粒填充的多孔介质内大Peclet数下双组分溶质在溶剂中流动、传质和反应的特性。因为LBM适合复杂几何边界问题，RWM适合大Pe数下的对流－扩散过程，本项目将发展格子玻兹曼方法(LBM)和随机游走颗粒追踪法(RWM)相耦合的数值方法，建立多孔介质内流体流动、传质和反应的数学模型。然后用LBM模拟多粒径分布颗粒沉积过程来构造随机的多孔介质几何模型。同时搭建固定床冷态试验台，进行不同填充粒径多孔介质内流动和传质过程的实验。实验和文献数据验证模型的有效性后，进行多粒径分布的多孔介质内大Pe数下双组分流动、传质和反应过程的数值模拟。所获得的大Pe数和粒径分布对多孔介质内流动、传质和反应的影响规律，可为固定床反应器内部构型设计和操作优化控制提供理论指导。

本项目以解决固体酸烷基化固定床反应器的多孔介质内部结构设计和操作优化控制为研究背景，以数值模拟为主、结合实验和文献数据验证，系统地研究多粒径分布的球形颗粒填充的多孔介质内大Peclet（Pe）数下溶质在溶剂中流动、传热和传质的特性。因为LBM适合复杂几何边界问题，RWM适合大Pe数下的对流－扩散过程，发展格子玻兹曼方法(LBM)和随机游走颗粒追踪法(RWM)相耦合的数值方法，建立孔隙尺度上多孔介质内流体流动、传质和反应的数学模型；同时建立了REV尺度上LB多孔介质内流动、传热和传质数学模型。搭建上流式反应器冷态试验台，进行不同填充粒径、颗粒密度、流体粘度下，多孔介质构成的床层内流动和传质过程的实验。然后用LBM模拟颗粒沉积过程来随机构造均质和非均质的颗粒填充型多孔介质几何模型，同时基于二维的Voronoi图构建了均质和非均质结构的毛细管型多孔介质几何模型。验证所建数学模型和数值方法的有效性后，进行孔隙尺度上和REV尺度上均质和非均质多孔介质内大Pe数下流动、传热和传质过程的数值模拟。根据均质和非均质多孔介质内流动、传热和传质的影响规律，从而进行床层内部构型设计和操作优化控制。